An article in "Automobiltechnische Zeitschrift" 84th year, 1982, No. 2, pages 77 and 78 describes an airbag safety system in which a filter surrounds the combustion chamber radially outwardly with the gas generator in the center for installation in a steering wheel of a motor vehicle. Such a structure is substantially limited for use inside the steering wheel to soften impacts between the driver and the steering wheel. Use of this known system for protecting the passenger on the front seat does not seem to be practical.
German Patent Publication No. 2,915,202 (Nilsson et al.) also describes an airbag inflating system with a concentric arrangement of the components relative to each other. Hence, that known system is subject to the same limitations as the one described above. The components of the known gas generator are made primarily of sheet metal.
Tubular gas generators for inflating a safety bag on the passenger side, in which the ignition, the combustion, and the filter casings, which have radially extending gas discharge openings, are arranged in axial alignment with each other along the length of the generator, are known in the prior art. In such generators the large surface chamber walls are exposed to unnecessarily high compressive loads, which must be taken up by thicker walls requiring higher material expenditures. Where the gas distribution is radially directed, unfavorable conditions prevail for a particleseparating by re-routing of the gases. An insertion of expensive filter material becomes necessary along the entire length of the gas generator.
Another unfavorable characteristic of the above mentioned conventional tubular gas generators is that during an alteration in the power rating, that is, when it is necessary to change the amount of propellent, not only the combustion chamber, but all the other components, such as the ignition chamber and filter components, must be altered.
German Patent Publication No. 2,330,194 (Wolf et al.) describes a conventional tubular gas generator for inflating a safety bag in a motor vehicle. The combustion chamber is formed in a tubular gas generator inner housing received in an outer housing. Labyrinth type mufflers are arranged radially or axially relative to the combustion chamber. In both instances the known system takes up substantial space. Further disadvantages are seen in that flange rings and baseplates, which are protected by two outer covers that are screwed into the outer housing, not only exhibit a limited stability or strength, but also an insufficient sealing of the outer housing. For this reason, the combustion chamber was arranged separately within the outer housing, which brings about considerable complications, especially in the assembly of the known structure, and rather large dimensions.
Conventional gas generator systems as described above have the disadvantage, that, especially in the tubular version, they further require two gas generators with two igniters and the accompanying cables and plugs. Said systems also need a double output stage in the impact sensor for activating both igniters. As a result, costs are high and integration into the other vehicle structures is not easy.